Their parsing is done with a completely different config parser, so things like filters, $variables,

[ar@is-a.cat]

Their parsing is done with a completely different config parser, so things like filters, $variables, !includes and <files don’t work

https://doc.dovecot.org/2.3/configuration_manual/config_file/#external-config-files

Thanks, dovecot.

[jernej__s@infosec.exchange]

@ar Don't worry, once you upgrade to 2.4, you'll have to rewrite all of your config files anyway, because the format is now completely different.

[ar@is-a.cat]

@jernej__s joke's on you, i already migrated to 2.4 on my own machines.
this is a piece of infrastructure shared with other people